Between 27 May and 4 June 1940, over 338,000 troops of the British Expeditionary Force (BEF) and the French Army, trapped along the northern coast of France, were rescued in the Dunkirk evacuation.[13] After the German Army invaded the Soviet Union in June 1941, the Soviet leader Joseph Stalin began pressing for the creation of a second front in western Europe.[14] In late May 1942 the Soviet Union and the United States made a joint announcement that a "... full understanding was reached with regard to the urgent tasks of creating a second front in Europe in 1942."[15] However, British Prime Minister Winston Churchill persuaded American President Franklin D. Roosevelt to postpone the promised invasion as, even with American help, the Allies did not have adequate forces for such an activity.